Heretofore, photographic materials suitably used for direct x-ray exposure have usually been designed and manufactured by coating on a transparent support at least one light-sensitive silver halide emulsion layer and incorporating a bluish dye either in the support or in a hydrophilic colloidal layer to be provided thereon, making an image-observer easier upon diagnostic observation.
In other words, most photographic materials for radiographic use incorporate a plan for displaying a developed silver image, which originally has a yellowish color, to be seen in bluish black in color when it is placed on a display board.
Some photographic films using a non-colored or clear base support has a disadvantage that the developed silver image, which bears reddish or yellowish color, tends to give the observer a feelings of physical and mental fatigue. Thus since prior state of the art has given priority to apparent beauty rather than diagnostic distinguishability of the image. This has been done by setting density through a blue light (Db) at a high level, which has lead to degrading of distinguishability of the image, particularly in the low density region thereof. This has, to a no small extent, disturbed medical diagnosis of the image.
Thus a technique which enables a diagnostic observer to easily give his diagnosis from an image having improved distinguishability throughout the whole density range of the image, without degrading quality of the image as a picture per se, as been a long-felt demand in the art.